The present invention relates to a blood sampling device that incorporates a lancet for piercing the skin and an adjustable end cap for regulating the depth to which the lancet pierces the skin.
Various types of blood sampling devices for drawing a blood sample from a skin puncture made by a lancet have been described. For example, U.S. Pat. No. 5,368,047 to Suzuki, et al. discloses a blood sampling device that has a lancet connected to a spring-loaded plunger that is reciprocable in a cylindrical housing between a retracted position and an extended position. The plunger has a gasket which makes sealing contact with the interior wall of the housing when the plunger is moved from its extended position to its retracted position.
Various mechanisms for adjusting the depth of a puncture made by a blood sampling device have been provided. For example, U.S. Pat. No. 5,554,166 to Lange, et al. discloses a blood lancet device for withdrawing blood that is provided with an adjustable end cap that is threadably coupled to the lancet device. After every use of a blood sampling device, the used lancet is discarded and a new lancet is attached to prevent the spread of communicable diseases. Use of a blood sampling device with a threaded end cap which must be unscrewed from the device in order to change the lancet can be unduly time consuming.
Other conventional methods of adjusting the depth of puncture have included providing a blood sampling device with different-sized frictionally retained unthreaded end caps which may be slid onto the housing of the device in a direction parallel to the lancing direction, such as the blood sampling devices marketed by Bayer Corporation under the trademark "Glucolet." To make a relatively deep puncture with such a device, an end cap having a relatively short length is used, and to make a relatively shallow puncture, an end cap having a relatively long length is used. However, the need to provide multiple end caps with each blood sampling device is not optimal.